Railway signal control system



Feb. 13, 1940. A. BROWN 2,189,879

RAILWAY SIGNAL CONTROL SYSTEM Filed Sept. 9, 1936 2 Sheets-Sheet 1 FIG.1.

ATTORN EY Feb. 13, A. BROWN RAILWAY SIGNAL CONTROL SYSTEM Filed Sept. 9,1936 2 Sheets-Sheet 2 5x4 Q I INVENTO R A/VD/PEW BROWN ATTO R N EYPatented Feb. 13, 1940 PATENT OFFICE RAILWAY SIGNAL CONTROL SYSTEMAndrew Brown, London, England, assignor to International StandardElectric Corporation,

New York, N. Y.

Application September 9, 1936, Serial No. 99,938

In Great Britain September 11, 1935 9 Claims.

This invention relates to railway or like signal control systems of thekind in which the signal for a particular section of track isautomatically I set to danger on a train entering that section,

the number of wheels on the train is automatically counted as the trainenters a section and also as the train leaves the section and the signalis only permitted to indicate that the track is 3 clear if the samenumber of wheels has been automatically counted out of the section aswas automatically counted into the section.

In such a system it may sometimes happen that 7 'due to some error inthe working of the apparatus, the counting apparatus has not returned toits original position when a train has left the section and thereforethat the signal is left at danger. Means have previously been proposedfor manually restoring the counting apparatus to normal position and forthus restoring the signal to clear. It is obvious that such restorationmust not be permitted until it has been ascertained that the tracksection is in fact clear and it is therefore necessary that a man shouldbe sent to examine the track section before this 25 manual restorationtakes place. There is some danger that restoration to normal may takeplace before proper examination of the track sections. The presentinvention allows of the counting apparatus to be restored to normalwithout this 30 danger. The counting apparatus may be restored to normalposition whilst leaving the signal at danger. With the signal in thisposition the driver of a train is permitted, after waiting a specifiedtime, to proceed at caution. Means 35 may be provided to display aspecial signal in these circumstances to inform a driver that he mayproceed at caution.

The restoration of the counting apparatus to normal position maybe donemanually or auto- 40 matically. If a train then passes through the tracksection at caution and the counting apparatus functions correctly tocount in and out the same number of wheels the signal may be restored toclear, but provision may be made 45 that two trains must pass throughthe track section at caution and be counted in and out correctly beforethe signal is restored to clear.

The nature of the invention will be clear from the following descriptiontaken in conjunction 50 with the accompanying drawings which show thecircuits of an arrangement for counting the wheels of a train into andout of a single track section. Fig.1 shows the circuits for an automaticres- 5 toration;

Fig. 1A shows additional circuits for use with the circuits of Fig. 1 ina modification of the structure; and

Fig. 2 the circuits for a manual restoration of the counting apparatusto normal position. 5 Referring now to Fig. l the contacts of thetreadles at the entrance to and exit from the track section denoted byET and LT respectively, are normally closed, and normally maintainrelays TRA and 'I'RB respectively, in operated condition. Theindications /l, /2, etc., following the reference to the relaysthroughout the drawings, indicate, the number of contacts controlled bythese relays. The circuit LC maintains the signals at clear when closed.This circuit includes normally closed contacts lrl and W3 of the relaysLR and GR respectively. The guard relay GR. is normally energized in acircuit including back contacts tqzr3, its own front contacts grl andfront contacts tral. The line LR relay is maintained energized overfront contacts 5712, front contacts trbl. and contacts of the switch 10for the impulseswhen in normalposition. l

The switch IC is schematically shown as two completely independentrotary switches RMA and RMIB, each of the well known non-homingstep-by-step type, having corresponding contacts connected together. Itwill be understood that in actual construction ICJ may be a singlecombined incounting and outcounting switch of any well known type,having two separate actuating magnets and two independent sets of wipersso arranged as to be electrically equivalent to two step-by-stepswitches multipled as shown. Since, however, the construction of such acombined switch is not readily adaptable to simple schematicrepresentations, this switch has been shown in the conventional mannerand will be described as if its incounting and outcounting portions wereseparate switches structurally independent of each other. Forconvenience in description, the relative position of the wipers 7 shownin the drawings (in which the wiper of RMA and the main wiper I0 of RMBrest on contacts which are connected together) is referred to as thenormal position of the switch. The switch wipers are illustrated asbeing pro- 1 vided with two wiper arms, so that upon reaching theextreme lower contacts by one arm, the other arm will reach the uppercontact and thus continue to operate. Regardless of the rotary positionof the respective wipers of switch por- R tions RMA and RMB, the normalposition exists so long as the two wipers above mentioned rest on thecontacts which are connected together.

The normal operation of the system will now be described assuming that atrain enters and leaves the section at a substantially constantpredetermined rate of speed.

Each wheel entering the track section opens contacts ET and de-energisesrelay TRA. This relay breaks the circuit of relay GR at tml on its firstde-energisation andso causes interruption of the circuit LG by opening.0 3, to set the signal for the track section at danger. gization ofrelay GR permitsits contacts g?" l to open thus maintaining relayGRde-energized,

and also opens circuit LC'at 9 3. Contacts 1 2 also close the circuit ofthe magnet'RMA which steps the incounting portion of the switch ICforward one step for each operation. This operation continues, theswitchportion RMA stepping forward one step for each' wheel entering thesection until all the entering whe'els h'ave' been counted in. Theswitch portion RMA will then be in advance of theswitch portion 'RMB bya"number"of"contacts dependent upon the number of wheels of the train.

" As the tram leaves the, track section each wheel successivelylopen'scontacts LT and de-energiz'es relay TRBL Deenergization of this relaycloses,

at contacts trbZ, the circuit of magnetRMB which steps the outcountingportion RMB of the switch IC forwardone step for each operation. .As theoutcounting portionRMB' of this'switch reaches a point'two stepsbehindnormaLthe relay GR'is' contacts or! and front contacts tral'. Thisenergization of relay 'GR'al's'o closes contact W2 and ra. When theswitch portion RMB'again reaches normal position the relay LR isenergized over contacts'yfl and contacts trbl. The signal is restoredtoclear by circuit LC. 4

- Should there by any'failure in the operation Of theswitcl'i So that itfails to take the same number of steps for both the incountingand'outcounting impulss'after'atrain hasleft the track section; switchportion RMB will not reach normal'position and relay LR willrem'ai'nde-energized leaving cir'cuit'LC open at lrjland the signal willremain at danger. i

In order that the switch IC may be restored to normalleaving, the signalat danger'further' circuits are provided. I

D'e energi'zation of the outcounting relay TRB closes contacts trb2completing a circuit over said contactsand contacts 7511.124 for relayTQ.

This relay is slow to release and designed toremain energized during theoutcountin'gimpulses as a train passes mm the sectionat an ordinaryspeed. RelayfllQ closes at contacts iii/2 the circuit'of ahigh-resistancewinding' of a thermal relay TH in serieswith ala mp'*-L.As the circuit through -theflampcorripleted relay TH is energized overacircuit starting'from positive supply through'the filament of lamp L,contact tq2 and the-high resistance winding of relay TH. If this circuitremained complete the current would'heat filamento'f lamp-L causing itsresistance to rise to such a value that the current would beinsuflicient'tohold TH operated. Before such heatin'goccurs a shortc'ircuit path isestablished around thela'rn-p b'y' closing of contact th! from positivebattery-through"contact tql which was closed upon op'eratioriof relay TQAt changeover further effect.

sistance winding of relay TH from positive sup ply through filament oflamp L, contact th3, low

resistance winding of relay TH, back contact of .tq3 and'contact 'thl.The low resistance winding and the lamp are shunted by a resistance Rbut sufficient current flows in the winding to maintain it operated.'After an interval the resistance of the lamp increases due to heatingof the filament to a sufficient extent to so reduce the current throughthe winding of relay TH as to cause-the relay TH to release itsarmature. If the number of outoounting' impulses correspondedj wi th thenumber of incomingimpulses will be in its normal position and relay LRwill again be energized; This will open cont'actlrgand release ofcontact thZ will have no 1 Slow release relay TQC will release after aninterval whether or not LR is operated and the circuit will be restoredto normal "unoperatedcondition.

' If; howe er, at the conclusion of the outcounting-impulses, relayLRremains de-energized,-i. e.,

Jeaher'spm error has occurred in' the counting I operations, orthere isstill a train, or a portion of 'a train 'withinthe track section, thereis before release of TQC a circuitestablished over contacts When thetrain has left the section, 7

ZrZ, back contact thZ, front contacts tqcl and winding relay- TQXbecomesenergized.

Relay HR'is energized over a circuit from positive supplyover contactZ12, winding of relay HR, front contact of tqzt5. Magnet RMB isenergized over a circuit traced from positive supply over 1m, winding ofmagnetRMB and contact tqwZ. The opening of contacts tqmll, however,prevents the re-nerg-iz'aagn r rela 'IQ. The magnet is energized'tocause the outcounting portion of the'switch to take one step. Theinterrupter or pulsing .contacts rmb break the circuit o fHRwhichd-energizes and breaks the circuit of RMB. The interrupter contactsagain close repeating the cycleof operation outlined above. I

"This outcounting stepping of the switch continues by the interaction ofmagnet RMB and relay HR until the switch reaches the normal position. jv

At iq 3 the circuit by which the relay GR is normally energized when theswitch portion RMB is two steps behind the normal position is broken andthe relay GR is thus prevented from re energizing. A circuit is closedover switch portion RMA, switch portion RMB, contact trbl, contact tqwland winding for the relay LR when the switch portion RMB reaches thenormal position. When LR becomes energized the circuit for HR is brokenat. Z72 and the circuit for magnet RlVlB is b-rokenat hv'l the relay TQXde-energizes contacts tqmB to close a circuit for relayAR to give such asignal. Relay AR then closes a locking circuit for itself over its owncontactsarl and the normally closed contacts tral of .th incountingrelay TRA.

If, after restoration of the switch IC to normal, without restoration ofthe signal to clear as described above, a train subsequently passesthrough the section and causes the same number of incounting andoutcounting impulses, the signal will be returned to clear by theoperation described below. The wheels passing over incounting treadle EToperate to step switchpor tion RMA ahead as fully described above.Similarly the outcounting treadle LT subsequently operates to advanceswitch portion RMB toward normal. Relay TQX will be deenergized byopening of its circuit at back contact th! when relay TH operates tomove contact thZ to its front contact. Deenergization of TQX permits theclosing of back contact tqm3 preparing a circuit for GR from lowermember of switch portion RMB through contact tqa:3 and winding of relayGR. When switch portion RlVLB advances to a point two steps behindswitch portion RMA the circuit of relay GR is completed and relay GR isenergized. Relay GR then closes a locking circuit by closing its frontcontact ml, and likewise closes contact 9T2, as fully described above.When switch portion RMB then reaches; normal position relay LR isenergized from positive supply over switch portion RMA, switch blade IDof switch portion RMB, contact trbl, contact mi and winding of relay LR.The circuit of LC is completed at Zr! and 913 and the signal restored toclear.

Thus the system provides a means for restoring the signal to clear, uponthe passing through the section of a second train proceeding at cautionand operating the switch correctly.

In another modification, the signal is not restored to clear until twotrains have passed through the section at caution and have been countedin and out correctly. For this purpose the additional circuits shown inFig. 1A are provided. A back contact of relay TPQ is included in thelocking circuit of the guard relay GR, and a back contact of relay TPOis included in the circuit LC.

When TQX is energized as described above it causes the restoration ofthe counting switch to normal position as described and also energizes arelay TPO through contact tqzr8 which closes a locking circuit foritself at tpol. When the first train is counted into and out of thesection correctly both LR and GR are energized, but the back contact ofrelay TPO included in the circuit LC prevents the signal being restoredto clear. A circuit is closed for relay TPQ through tpot which closes alocking circuit for itself at tpql and breaks the circuit of relay GR byopening the contact in the locking circuit. Relay TPQ also opens thelocking circuit for relay TPO at tpqZ, but as relay GR has de-energized,the signal remains at danger. Relay 'IPQ remains energized. On a secondtrain being counted in and out of the section correctly, the relays LRand GR are energized in normal manner at the conclusion of operations.Energization of relays GR and LR breaks the circuit of relay TPQ at m4and H3 restoring the circuits clear.

In a further modification, shown in Fig. 2 the switch may be restoredmanually to normal position without restoring the signal to clear. If atrain has entered and left the section and the signal remains at danger,thesignalman may actuate the key RK. This energizes relay TQX which thenperforms the same functions asin the automatic operation described inconnection with Fig. 1 and restores the switch to normal whilst keepingopen the circuit of the guard relay GR and thus maintaining .the signalat danger. The signal is then restored to clear upon the sub sequentcorrect, incounting and outcountingof a second train passing through thesection, and particularly described in connection with Fig. 1.

In this modification also, the restoration of the signal to clear may bedelayed until after .two trains have traversed the section and beencounted into and out of the section correctly, by the addition of therelays TPO TPQ and the modifications to the locking circuit of GR andthe circuit LO described above more particularly with reference to Fig.1A.

What is claimed is:

1. A railway or the like signal control system comprising a signal, asection of track, means for in-counting and out-counting the wheels of atrain into and out of said section, means controlled by said countingmeans for controlling said signal into danger if the number of wheelsregistered by the in-counting and out-counting differ, and into clear ifthe number of wheels registered by the in-counting and out-countingagree, means operative for establishing an operating circuit for saidcounting means without restoring said signal to clear when the signalhas been left at danger by a differing in-counting and out-counting ofwheels in the section, and means responsive to a subsequent agreeingincounting and out-counting operation for restoring said signal toclear.

2. A railway or the like signal control system comprising a signal, atrack section, wheel counting apparatus in said section for countingwheels into and out of said section, a signal, means controlled by saidcounting apparatus for controlling said signal to danger in response todisplacement of said counting apparatus from normal by a disagreement ofsaid in-counting and out-counting and into clear if said in-counting andoutcounting agree, means for returning said counting apparatus to normalwithout restoring said signal to clear after said counting apparatus hasbeen left out of normal by a disagreement in the in-counting andout-counting operation, and means responsive to a subsequent agreeingincounting and out-counting operation oil said counting means to restoresaid signal to clear.

3. A railway or the like signal control system as claimed in claim 2, inwhich said means for restoring said counting apparatus to normalcomprises means responsive to the condition that said signal remains atdanger for a predetermined time, on conclusion of said out-countingoperation for restoring said counting apparatus to normal while leavingthe signal at danger.

4. A railway or the like signal control system as claimed in claim 2, inwhich said means for restoring said counting apparatus to normal comprises relay means responsive to the condition that said signal remainsat danger for a predetermined time for restoring said apparatus tonormal, said responsive means including a lamp in series with a relay,said time being determined by the rise in the resistance of said lamp toa value sufficient to cause said relay to deenergize.

5. A railway or the like signal control system as claimed in claim 2, inwhich said means for as olaimed in claimfl, 1nv which said iii-counting'iapa out ou t ntingv means includes contacts ,0?" {m ratedpjz tlie'wheels of a rain S id contacts lgel g vnorn ally ol osedeand heingopened bythe p ssa'ge off a wneel of agt'ram.

"17A ailw ay or the like signal control. system ed inflclaim 2, ,inwhichisaid wheel count- I t'us Q'r'nprises contacts operatedby the eelsof ai traim' 'said contacts beingnormally closed ancl beingogened by thepassage of a {wheel rain.

A ailwaynor like signal control system as ,cl med Ljijri'claim 2, inwhich said means for restoring the counting apparatus to normal positionis manually operable, further comprising means 17,0- prevent suchrestoration from placing thevsignalfto clearposition until afteroperation I0 f, Said means responsive to subsequent correct counting. V

V9. A raflway orlike signal control system as claimed in claim 1,further comprising means iorvmaintainin'g the signal at danger until twotrains insuccessi'on have been counted into and but ,of the sectioncorrectly.

ANDREW BROWN.

